This post shows the steps I took to set up 2 private networks (192.168.1.1/24 and 192.168.2.1/24) using 2 routers. Not only does this gives me extended wifi coverage (also can be done using the router as Access Point), if I like, I can also have more control over the LANs (eg. prevent Internet access on 192.168.2.1).
I will not go into how to access the router using the web browser (which I did) or any applications as the nitty gritty could be specific to the routers. I will only list the settings which I made.
I used Router 1 as the primary router connected to the Internet and it will have 192.168.1.1/24 as the LAN addresses. Set up Router 1 to ensure that it functions and you can access the Internet as per normal.
Next, reserve 1 IP address in Router 1 for the WAN IP of Router 2. I will call this reserved IP as 192.168.1.2. You will need to use the IP reservation setting of Router 1 to do the reservation so that this IP address will not be used by other devices.
Still in Router 1, set its NAT such that all traffic going to 192.168.2.1/24 will be directed to 192.168.1.2. This is important - otherwise you may not be able to access 192.168.2.1/24 when connected to Router 1 and traffic will be routed to the Internet.
You should be done with Router 1.
Resetting Router 1 may be necessary.
Connect Router 2 to Router 1 using a LAN cable - one end to a ethernet port of Router 1 and the other end to the WAN port of Router 2.
Now connect your PC to Router 2 (I suggest giving it a factory reset) using a LAN cable.
Power up Router 2 and access its admin page. See your router documentation on how to do this.
Assign 192.168.2.1 as the IP address of Router 2. I used 255.255.255.0 as the subnet mask.
Assign 192.168.1.2 as the WAN IP (use static IP). I used 255.255.255.0 as the subnet mask. Still at the WAN setting, set the gateway of the WAN to 192.168.1.1. I set the DNS servers as 192.168.1.1 and 8.8.8.8 (Google DNS server).
Set the wifi setting (SSID, passphrase) of Router 2 to settings you desire (but SSID should be different from Router 1).
That should be it. You may need to restart Router.
You should be able to connect to the wifi of Router 2 and access the Internet and when connected to the wifi of Router 1, access devices connected to Router 2 (and vice versa).
You can enhance the security by fiddling with the firewall settings of the routers.
